26 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



Description. — Surface densely covered with sand grains. Test 

 soft, gelatinous, but impregnated with sand grains in layers of ab- 

 domen and postabdomen ; however thoracic layer quite free from sand 

 grains. Only 3 zooids comprise this small colony. Abdomen about 1.5 

 times the length of contracted thorax. Length about 2.5 mm. when 

 both thorax and abdomen are measured together. Postabdomen nearly 

 as long as abdomen. Both branchial and atrial apertures 6-lobed; 

 lobes of branchial aperture bifid, especially dorsal and ventral lobes. 

 Atrial aperture opening at tip of short siphon which arises at level 

 of first stigmatal row; atrial languet absent. About 15 longitudinal 

 muscles on each side of the thorax. Five stigmatal rows, each contain- 

 ing 12-15 stigmata. Anus situated at level of third transverse vessel. 

 Stomach located near middle of abdomen, longer than wide, with 4 

 longitudinal plications on free surface. Proximal end of rectum dis- 

 tinctly constricted from foregoing part of alimentary canal, but caeca 

 are formed only inconspicuously. Mature gonads not found in zooids 

 examined. 



Remarks. — Typical A. depressum has G or 7 (according to Van 

 Name, 1918), or up to 9 (according to Sluiter, 1909) rows of 

 stigmata on the branchial sac and about a dozen (Van Name, 1918) to 

 "zahlreiche" (Sluiter, 1909) longitudinal plications on the surface of 

 the stomach. In the present specimen, there are 5 stigmatal rows and 

 only 4 plications on the stomach. The difference in the number of 

 stigmatal rows may be insignificant, but the number of longitudinal 

 plications on the stomach is so remarkable that I hesitate to identify 

 the specimen as depressuin. It is possible that the specimen belongs to 

 another distinct species, yet it is not impossible that the specimen rep- 

 resents a very young stage of depressum and the longitudinal plica- 

 tions on the stomach may increase with the growth of the zooids or with 

 the growth of the colony. On the other hand, the appearance of the 

 atrial aperture, which is 6-lobed and devoid of atrial languet, resembles 

 exactly that of the Philippine specimens described by Van Name 

 (1918). For these reasons I prefer to treat the specimen as a form 

 near Aplidium depressum. 



3. Aplidium spitzbergense Harlmeyer 



FlGtTBE 3 



Aplidium spitzhergense Hartmeyer, 1903, p. 341, pi. 6, fig. 14; pi. 13, fig. 17, 

 Amaroucium spitzhergense Van Name, 1945, p. 30. 



MATERIAL EXAMINED 

 Bering Sea: Albatross sta. 3315. Two massive colonies; one is 11 mm. x 28 

 mm. in extent and 19 mm. in height, the other is only 4 mm. X 12 mm. in extent 

 (USNM 11734). 



Description. — The larger colony contains zooids preserved per- 

 fectly, although part of the colony is much mutilated, while the 



